Manufacture of synthetic polymeric filaments

ABSTRACT

A polyamide yarn and a method of producing a polyamide yarn which is substantially stable to length changes due to expansion and contraction in the presence of moisture and/or heat in a freshly drawn and relaxed condition. The yarn is produced by eliminating steam or other moisture conditioning normally associated with the spinning of polyamide yarns and effecting at least a partial drawing of said yarn in the freshly spun state prior to packaging such yarn. The produced yarn suffers substantially no length change, that is, length changes are limited to less than 1 percent in the presence of moisture and/or heat.

United States Patent Evans et al.

[54] MANUFACTURE OF SYNTHETIC POLYMERIC FILAMENTS [72] Inventors: Vincent L. Evans, Abergavenny;

Dennis A. Dyer, Cheltenham, both qfes eeq [22] Filed: May 20, 1965 [21] App1.No.: 457,279

[30] Foreign Application Priority Data May 28, 1964 Great Britain ..22,054/64 [52] US. Cl. ..264/210 F, 264/176 F, 264/342 R [51] Int.Cl. ..D0ld 7/04 [58] A Field of Search.....264/2l0 F, 176 F, 342, 342 R [56] References Cited UNITED STATES PATENTS 3,039,171 6/1962 Hume et al. ..264/342 [451 Sept. 26, 1972 FOREIGN PATENTS OR APPLICATIONS 758,398 10/1956 Great Britain ..264/210 Primary Examiner-Theodore Morris Attorney-D. .1. De Witt, Leonard Horn and L. I. Grim 5 7 ABSTRACT A polyamide yarn and a method of producing a polyamide yarn which is substantially stable to length changes due to expansion and contraction in the presence of moisture and/or heat in a freshly drawn and relaxed condition. The yarn is produced by eliminating steam or other moisture conditioning normally associated with the spinning of polyamide yarns and effecting at least a partial drawing of said yarn in the freshly spun state prior to packaging such yarn. The produced yarn suffers substantially no length change, that is, length changes are limited to less than 1 percent in the presence of moisture and/or heat.

1 Claim, 1 Drawing Figure MANUFACTURE OFSYNTHETIC POLYMERIC "-FILAMENTS This invention relates to the manufacture of synthetic'polymeric filaments, and is particularly concerned with the production of such filaments which are at least partially drawn and which are stable towards boiling water, i.e. the filaments neither shrink nor expand when immersed in boilingwate'r.

In the production of,. for example, polyhexamethyleneadipamide filaments by the conventional process,molten polymer is extruded into filamentary form through orificesicontained in a spinneret plate. The semi-molten filaments are rapidly quenched by a transverse blast of cold air, gathered together into one or more bundles, passed through a steam conditioning tube, over a finish roller and are then wound onto a yarn package orcheese. During this process a certain amount of draw-down occurs which results in some slight orientation of the filaments,jsuch filaments are nevertheless referred to, as being undrawn. if the filaments are wound onto a package as ayarn without having passed through a steam conditioning tube poor builds and package sloughing occurs owing to an increase in filament length which takes place as the filaments absorbmoisture from the aqueous finish or from the atmosphere.

In order to impart strength and other desirable characteristics to the yarn the undrawn yarn is drawn to at least three times its original length, and wound onto yarn packages usually by the ring and traveller system.

highly oriented and rise to a number of well-known defects in fabric form.

The boiling water shrinkage of such yarns may be as much as -11 percent.

The method of measuring the boiling'water shrinkage of .filaments employed for the purpose of this description is as follows: A 100 cm. length of yarn is doubled and weighted at the rate of 0.003 gmsQ/denier andwholly suspended in boiling water for minutes. At the end of this time the sample is removed and suspended in the ambient atmosphere at a relative humidity of 59- 71 percent and a temperature of 64 80 F for 1 hour at the end of which time the length of the sample is determined and the percentage shrinkage calculated.

In drawn yarns the shrinkage effect which is observed is considered to be the result of the relief of the strains set up in the drawing process. in fact it is thought that there are two opposing effects:

1. yarn shrinkage which results from the relief of strain and 2. yarn growth which is thought to result from an increase in orientation and cystrallinity as moisture enters the yarn. and that it is the sum of the effects which is measured. In the case of conventionally spun and drawn yarns the first of these effects predominates to a marked degree. it would be an advantage to produce yarns which are at least partially drawn and which exhibit neither a decrease or an increase in length since such yarns would result in more stable packages being obtained and would also avoid problems associated with barre.

It would be an additional advantage if at least partially drawn yarns could be produced by a process which dispenses with the use of a steam conditioner tube.

the presence of moisture and/or heat whilst in a relaxed condition, can be produced by spinning the yarn in the absence of a steam conditioner tube and other sources of moisture and, immediately after spinning, drawing the yarn to a given degree of orientation. The amount to which the yarn can be drawn whilst retaining the desirable propertiesin the yarn will depend upon the ambient humidity and undrawn denier.

it is thought that with yarn produced by this process the two effects hereinbefore referred to are equal and opposite, thus making the yarn stable.

Accordingly therefore, the present invention provides an at least partially oriented polyamide yarn which, in the freshly drawn state and in a relaxed condition, is stable in the presence of moisture and heat, i.e. the filament or yarn suffers substantially no length change when subjected to the action of said moisture or heat.

According to another aspect the present invention provides a process for the manufacture of an at least partially oriented polyamide yarn as hereinbefore defined, comprising extruding the molten polyamide through a spinneret plate containing one or more extrusion orifices into one or more filaments cooling the filament or filaments and orienting the filament or filaments to a predetermined degree under substantially moisture-free contitions that is, without direct additions of moisture such as steam conditioning or the application of aqueous finishes and winding up the drawn filament or filaments onto a package as a yarn. The

'orientating of the filament is conveniently done under ambient atmospheric humidity conditions.

Preferably the filaments are oriented by forming them into a bundle at a yarn guide after cooling, applying a non-aqueous finish thereto and then drawing the bundle by the required draw ratio between two sets of rollers, the second set running at a greater peripheral speed than the first.

The drawn yarn may be wound up onto a cheese in which case it will be substantially twistless and is in a suitable form for applying a further drawing operation should this be desirable, or it may be wound onto a container by the ring and traveller system in which case a small amount of twist will be imparted to the yarn.

A preferred process for producing a yarn of this invention will now be more fully described with reference to the accompanying drawing.

In the drawing:

FIG. 1 is a diagrammatic representation of an apparatus for spin-drawing a polyamide yarn.

Filaments l and 2 are obtained by extrusion of a molten polymer through orifices contained in the spinneret plates 3 and 4 and are cooled in spinning chimney 5 by a transverse blast of air. The filaments are combined into a single bundle at guide 6 and are passed over finish roll 7 between guides 6 and 8. The bundle of filaments are then drawn between the feed and separator rolls 9 and 10 and the draw and separator rolls l2 and 13, the point of draw being 1 located at fixed point by the snubbing pin 1 l, and wound up onto the cheese l4.

The following example illustrates, but does not limit, the process of this invention using the apparatus described above.

EXAMPLE Polyhexamethylene adipamide polymer containing 0.03 percent of TiO and having a relative viscosity of 33 is spun through a spinneret plate containing 80 circular orifices at a spinning speed of IOOOft/min. to give a constant denier of 2,200. The as-spun filaments are cooled in the spinning chimney by a transverse blast of cold air and after solidification are gathered together into a single bundle at a guide and then passed over a finish roll rotating at a speed of 2 rpm. to apply a nonaqueous oil finish comprising dibutyl sebacate and a non-ionic surfactant sold under the name of Marchon 5639. The bundles of filaments are then drawn at a draw ratio of 1.9 and wound up onto a cheese.

The physical properties of the yarn were as follows:

Denier 1040 Tenacity 1.95 gm/d.

Extension to break 160 percent A sample of this yarn had a boiling water shrinkage of less than 0.5 percent when tested as hereinbefore described.

In the above example no effort was made to prevent the absorption of moisture by the filaments from the cooling air or from the ambient atmosphere during the finish application and drawing steps. It is expected that higher draw ratios may be exployed by ensuring the complete absence of moisture during spinning, finish application and drawing, thus increasing the degree of orientation of the yarn and hence improving its physical properties.

The process of this invention is not limited to drawing by the method described above, thus the yarn may, for example, be drawn by passage through an aspirating jet in which it is drawn by a high velocity stream of gaseous fluid such as air.

What we claim is:

l. A process for the manufacture of a partially orientated polyamide yarn comprising extruding a molten polyamide through at least one orifice contained in a spinneret plate into at least one filament, cooling the filament and drawing it by means of a high velocity stream of a gaseous fluid at a draw ratio sufficient to effeet a subsequent contraction in the relaxed state commensurate with the expansion effected on the subsequent absorption of moisture, said spinning and drawing being effected at ambient humidity conditions without the direct addition of moisture to the filament and winding up the filament onto a package as yarn. 

